Method of making coils



Sept. 10,1935. J. P. PUTNAM METHOD OF MAKING COILS Original Filed Aug. 9, 1953 Patented Sept. 10, 1935 UNITED STATES PATENT OFFICE METHOD OF MAKING COILS John P. Putnam, Boston, Mass., assignor to The Reece Button Hole Machine Company, Boston, M, a corporation of Maine Original application August 9, 1933, Serial No. 884,407. Divided and this application October 31, 1934, Serial No. 750,843

3 Claims. (Cl.- 140- 71) This invention relates to a method of produc-' ing concaved wire coils, such as are used in a spherical variometer. The invention particularly involves the method ofmaking a concaved universal or cross-wound coil, and is a division of my application Serial No. 684,407, flied August 9, 1933 for a variometer.

Spherical variometers are old in -the radio art, but in the past have been dimcult and expensive to manufacture and of such large physical bulk as to be impractical. Heretofore concave coils have had to be wound very expensively by hand, in a single layer, or as layer wound coils on a basket-like frame work, of poor electrical qualities and occupying too large a space in aset to make them practical. For these various reasons the honeycomb coils, basketweave coils, bankwound, and helical coils of the prior art have been unsatisfactory. Recently a coil of high inductance has been wound in the form of a flat annular ring or disk, using the so-called universal or cross-wound winding. Such coils, however, could not be satisfactorily wound in a concaved form for use on a spherical variometer. My invention relates to the method 'of making such concaved cross-wound coils and comprises placing the flat annular ring or disk in a suitable die and concaving the same by impact.

In the drawing:

Fig. 1 is a perspective view of a coil wound in flat annular form;

Fig. 2 is a perspective view of the same coil, as concaved;

Fig. 3 is an enlarged side elevation of a universal wound coil showing its construction;

Fig. 4 is a side elevational view of the die part used in concaving the coil, shown in separated relation;

Fig. 5 is a vertical cross sectional view of the die part used in concaving the coil, in assembled relation.

Before explaining in detail the present invention it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawing, since the invention is capable of other embodiments and of beingpracticed or carried out in various ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation, and it is not intended to limit theinvention claimed herein beyond the requirements of the prior art.

In the drawing, l0 represents a flat annular cross-wound coil, before concaving. The .uni-

versal or cross-wound coil, known also to the textile and radio trade as a diagonal or V- wind coil" or package is wound on a cylindrical rotating core by a machine having 'a thread arm which oscillates axially from side to side as the coil is rotated, thus giving each strand an undulating or waving motion as it is built onto the core. The coil may be wound to a thickness of 3%, having three or four turns per layer;

the turns of each radial layer being wound at an angle to those of the preceding layer, crossing and then binding them in place. v Thewire is laid in helices which extend from one edge of the coil to the other and back again with the turns crossing each other at sharp angles at regular intervals, the wind reversing with a sharp bend and each turn crossing over the next preceding layer binding it in place at each crossing. Thus from the nature of the winding each group of three or four strands, comprising a radial layer of strands, is twisted or turned over on itself at the top and bottom parts of each wave. Such a coil is illustrated in enlarged view in Fig. 3. The accuracy of winding is such that the individual turns of alternate radial layers can be laid in exactly the same radial plane, resulting in the building of an extremely rigid and self-sustaining coil. This method of winding a self-sustaining coil or package is widely used in the textile trade for producing cops or packages of yarn and thread. This method of winding was first described in United States Patent No. 480,158 to Simon W. Wardwell, granted August 2, 1892. The dominant characteristic of the so-called universal system" is that each helix extends a suflicient distance in one direction so that it binds and holds the next proceeding reverse helix and is bound and held by the reverse helix next succeeding. The wire coil for radio use is usually further held together by being saturated with a dope or adhesive such as paraflln. When wound in this manner the coil forms a highly efllcient inductance coil of high inductance, much superior to single and multi-layer coils. 45

The flat annular coils Ill wound as just dev scribed, I adapt for use with a variometer by concaving them to form rotor and stator coils. The

coils are concaved by placing them preferably in a suitable die and pressing them into shape. To 50 avoid breakage of the coils, they should be shaped by the impact of a sharp blow in the die, rather than by slow pressure. The die that I have used,

illustrated in Figs. 4 and 5, comprises a female member l5 having a suitable concavity therein 55 IS, a removable core I! for holding the coil in position, guide posts l8, and a male member IS with a convex portion 20. The male portion I9 is provided with holes 21 for sliding on guide posts I8. When compressed in this die, the coils have received a concave shape suitable to form rotor and stator coils. This is the first practical and inexpensive method of making compact hemispherical coils of small size yet high inductance as far as I am aware. The coils when carefully compressed in an accurately made die, are

formed to proper shape without mutilation or danger of short-circuiting, which would prevent uniformity of inductance in the case of a number .of such coils. By utilizing the flat annular universal or cross-wound coil, and concaving it in a suitable die, I have been able to produce a highly successful'variometer of high efiiciency, inexpensively made and which occupies a very small space.

I claim:

1. The method of producing a wire coil which consists in winding a fiat annular coil and then subjecting the coil to force between suitable dies to produce a concavo-convex coil.

2. The method of producing a concaved cross wound wire coil which consists in-winding a flat annular cross-wound coil and then subjecting the coil to force between complementary convex and concave die members.

3. The method of producing a concaved crosswound wire'coil which consists in winding a flat annular cross-wound coil, placing the coil on a cylindrical core and compressing it' between complementary convex and concave die members.

JOHN P. PUTNAM. 

